follow @PCDSUKCreated: 5th May 2016 | Last Updated: 4th July 2016
Introduction
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Oculocutaneous albinism (OCA) is a rare genetic disorder characterised by generalised depigmentation of the skin, hair and eyes, with ophthalmological anomalies. It is caused by a deficiency in melanin biosynthesis. Affected individuals have very fair skin, which is prone to sunburn, white or a very light coloured hair, and they may squint a lot as their eyes are sensitive to sunlight. This chapter is set out as follows: |
Aetiology
- Albinism is mostly a recessively inherited condition, which means that two albinism genes need to be inherited, one from each parent
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Oculocutaneous albinism (OCA)
- Is due to a deficiency of melanin biosynthesis, as opposed to a lack of melanocytes, which are present in normal numbers. This reduction in melanin is responsible for the increased sensitivity to UV radiation and for a predisposition to skin cancer. The ophthalmological anomalies associated with albinism are not only a consequence of a lack of melanin but also of a lack of L‐DOPA, an early intermediate of the synthesis of melanin, which has been shown to be required for normal retinal and visual development
- OCA is the most frequent form of diffuse hypopigmentation worldwide with a prevalence estimated around 1/20000. There are various subtypes of OCA, OCA1 is the most frequent form worldwide, OCA2 is the most frequent form among African patients with a prevalence that reaches 1/1000 in some populations in Western Africa
- The term ocular albinism refers to a lack of melanin in the eyes, while the skin and hair appear normal or only slightly lighter - this accounts for 10-15% of all albinism cases
Clinical findings
- In OCA the pigmentation of the skin, hair and eyes is in general reduced but the degree varies with the type of albinism
- All types of OCA and ocular albinism (OA) have similar ocular findings, including photophobia, various degrees of congenital nystagmus, reduced visual acuity, hypopigmentation of the iris leading to iris translucency, and reduced pigmentation of the retinal pigment epithelium
Images
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Figure: 1 Oculocutaneous albinism |
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Figure: 2 Oculocutaneous albinism Sadly, in many parts of Africa people with albinism are misunderstood, disadvantaged, and even attacked and killed. Their body parts are sold to witchdoctors for use in charms and magical potions believed to bring wealth and good luck |
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Figure: 3 Oculocutaneous albinism and basosquamous carcinoma Original source Indian Journal of Dermatology, Venereology, and Leprology |
Management
- Sun protection is mandatory - the incidence of skin cancer is increased in patients with OCA, especially squamous cell carcinoma which is a cause of mortality in Africans with OCA2. Melanoma is far less common, suggesting that melanin production is a key factor for melanoma risk in the context of UV exposure
- Early referral to an ophthalmologist is necessary - decreased visual acuity is usually managed with corrective lenses while strabismus requires eye patching or surgical correction. Dark glasses are important to protect the eyes and prevent photophobia
- One concern that should not be overlooked is the risk of isolation in people with albinism. People with albinism, especially children need to be treated normally and included in all activities. They develop normally and have normal intelligence, it is a myth that people with albinism are mentally impaired or intellectually-challenged